Android

In the past day or so, I've been noticing these "Package file is invalid" errors on my Android devices while trying to upgrade or install certain packages from the Play Store. A bit of searching revealed that many others are having this problem, and various home remedies abound for trying to fix it, such as clearing the Play Store's app cache. Unfortunately, while these remedies may have worked for past problems that led to this error message being displayed, they are useless when trying to fix the issue people are experiencing this weekend.

I've been researching the idea of using embedded languages in mobile applications as a way of reusing business logic across platforms. I haven't found a lot of information about how much an embedded language will bloat an app's size, so I decided to see for myself. So far, I've written simple "Hello, world" apps for both Lua and Squirrel. Lua is a simple language that has been heavily used in video games for years. Squirrel is a newer language that was inspired by Lua, but uses a more C-like syntax.

While developing Android applications, I'm often juggling lots of Android machines, both real and virtual. Since I often need to connect to these machines over the network with adb connect, I found it useful and educational to write a small home screen widget that always shows the device's IP address. This is a pretty dumb application, but I decided that it would be a good opportunity to learn how to publish apps on the Android Market.

An on-screen trackpad and keyboard allow a computer to be remote controlled.

Valence supports mDNS service discovery (aka Bonjour or Avahi) to locate participating VNC servers on the local network.

In my spare cycles recently, I've been tinkering with developing Android code to control home theater components. As someone who has been passionately involved with the consumer electronics industry over the past ten years, my personal home theater system includes quite a collection of disparate devices that defy even the most feature-rich universal remote controls. What the world needs is an open, extensible Android remote control application that can be rapidly updated to support new devices as they are released.

In my previous post, I mentioned my frustration that certain Android phones (including my HTC EVO) cannot receive multicast datagrams. I'd like to get feedback from my friends and colleagues about multicast support on their phones, so I wrote a simple app for testing multicast.

The Multicast Test Tool continually monitors the network for Multicast DNS (mDNS) packets while the app is running in the foreground, and presents the contents of these packets to the user. The app also allows the user to perform simple mDNS queries on the local network. If you run the app and touch the "Query" button, it will query for the default _services._dns-sd._udp.local name, which will solicit mDNS responses from devices on your network that advertise services via mDNS.

It looks like some (most?) HTC phones running Android, such as my HTC EVO, are not capable of receiving multicast or broadcast datagram packets over the Wi-Fi network. This means that apps which rely on such communication will fail, often with no indication of the problem. From the app's perspective, no obvious error is happening — it can only assume that no other devices on the network are transmitting such datagrams. Multicast communication is becoming increasingly common as a technique for devices to discover each other on a network, and the absence of this capability represents serious breakage that leaves apps crippled. Examples of resources an app might use multicast to discover are:

HTC EVO, shown with the optional extended-life battery.

Earlier this year, I ditched my antiquated Treo 755p for the new hotness in mobile phones—the HTC EVO, an Android phone available from Sprint. Unlike my previous phone, which would last a full week in standby without recharging, the EVO gulps battery like there's no tomorrow. In fact, the limited battery life has been the primary complaint about the phone. Nobody seems to know for certain why the battery life is so poor. Maybe it's the beefy 1Ghz Snapdragon processor, the large LCD screen, or something else entirely.